Hydraulically damping bush bearing

ABSTRACT

A hydraulically damping bush bearing has an elongated inner part, and outer bush, an elastomeric damping member disposed between the inner part and outer bush and a pair of axial chambers offset from one another in an axial direction. The axial chambers communicate with one another via at least one axial channel. The bush bearing also has a pair of radial chambers that communicate via at least one radial channel. The radial chambers are disposed between the pair of axial chambers and are offset from each other in a circumferential direction. One of the pair of axial chambers has at least two separated first axial chambers spaced at a distance from one another in the circumferential direction.

FIELD OF THE INVENTION Background of the Invention

A hydraulically damping bush bearing of this type is known from DE 10359 340 A1 and also has a pair of axial chambers with at least two axialchambers arranged offset from one another in the axial direction of theinner part and communicating with one another via at least one axialchamber channel. Moreover, a pair of radial chambers with at least tworadial chambers, communicating via at least one radial channel, whichare arranged between the axial chambers and offset in thecircumferential direction of the inner part, is provided. In genericbush bearings, the inner part generally has a hole for receiving an axlepin of a machine element or component to be mounted.

Generic hydraulically damping bush bearings are used mainly inautomotive engineering to mount parts of the wheel suspension or driveassemblies of vehicles. In addition to elastic damping elements, whichare typically made from an elastomer, the hydraulically damping bushbearing comprises chambers for receiving a hydraulic damping fluid thatsupports damping. To utilise the dissipating effect caused by the weightof liquid, chambers are provided in the elastomeric insert parts orrubber bodies of the hydraulically damping bush bearings to receive afluid damping agent. The exact size and position of the chambers dependson the intended use of the hydraulically damping bearing, moreparticularly the respective desired dissipating effects in an axial,i.e. longitudinal direction of the inner part and a direction at rightangles thereto, i.e. radial direction. The oscillation characteristicsof the component to be mounted are also important as well as the deadweight of the damping mass to be mounted. In any case, the chambers aretypically interconnected by one or more channels. Depending on thestress on the bearing, the hydraulic damping agent can thus be pressedfrom one chamber into another. Both bearings in which the hydraulicdamping is used in respect to forces introduced radially into the bushbearing and bearings in which mainly the damping is supported by thedamping fluid are known in this connection. The prior art referred toabove is evidence of a bush bearing in which the amortising effect isutilised in both an axial and a radial direction.

It has been shown, however, that when generic hydraulically damping bushbearings are exposed to higher frequency oscillations, more particularlyoscillations ranging between 50 Hz and 150 Hz, in particular >250 Hz, ofthe component to be mounted in a damping manner, unintentionally highdamping occurs and thus hardening. The required damping by means of thehydraulically damping bush bearing is no longer guaranteed in thedesired manner at said higher frequencies.

SUMMARY OF THE INVENTION

The present invention is based on the problem of providing ahydraulically damping bush bearing, which also demonstrates good dampingat higher frequencies. The present invention intends to provide ahydraulically damping bush bearing, which does not createunintentionally high damping in a radial direction at higherfrequencies. The hydraulic damping bearing is intended to prevent thehardening step observed in the prior art at higher frequencies aboveapprox. 250 Hz, and more particularly in the case of radial damping.

To solve the above-mentioned problem, the present invention suggests ahydraulically damping bush bearing with the features discussed herein.

The hydraulically damping bush bearing has an elongated inner part as isknown. Said elongated inner part has a hole running along thelongitudinal axis which can also be configured as a blind hole, i.e. notcontinuous. The hole generally runs in the longitudinal direction of theelongated inner part, which is shaped as a sleeve. To one side, saidinner part typically towers above said stop plate, which is used tomount the engine element or component to be damped. Typically, an axialchamber configured continuously in a circumferential direction is alsolocated on said connection side, which chamber communicates with anaxial compensating chamber on another side of the bush bearing via atleast one axial channel.

Moreover, the hydraulically damping bush bearing preferably comprisesadditional elements, which perform different functions. If there are tworadial chambers, only two additional elements can be provided. Theadditional elements extend firstly along indentations formed by theelastomeric damping member for the radial chambers and formcorresponding lateral faces for said radial chambers. The additionalelements are typically supported in a radially outward direction on abush bordering the bush bearing at the outer circumference and serve asa radial stop, which prevents excessive radial oscillation of the bushbearing with the displacement of the damping fluid provided in bothradial chambers. Moreover, the additional elements generally form theaforesaid radial and axial channels between the outer peripheral surfaceof the additional elements and the inner peripheral surface of the bush.Depending on the tuning of the frequency position for the dampingmaximum, the channels can be long, short broad or narrow. An axialchannel connects the at least two axial chambers of the pair of axialchambers. The axial channel (s) does not typically extend strictly in anaxial direction, but also run in a circumferential direction.Furthermore, said additional elements form the at least one radialchannel which connects the radial chambers to one another. Said radialchannel is typically configured in the additional elements as runningsolely in the circumferential direction. Several additional elementsgenerally constitute a cylindrical component in a fitted together state,the outer peripheral surface of which is provided with the recessesforming the radial and axial channels. The axial extension of theadditional elements is at the level of the radial chambers, i.e. wherethe additional elements engage with the indentations formed by theelastomeric damping member, lower than between said radial chambers. Theadditional elements typically extend in an axial direction between theradial chambers from the aforesaid axial compensating chamber more orless to the other axial chamber.

According to the invention, at least on one side of the radial chambers,the axial chamber provided there is sub-divided. A plurality ofseparated, first axial chambers spaced at a distance from one anotherare located on said one side. Thus, the damping fluid on said one side,which typically is opposite the connection side, cannot circulate freelyin the axial chamber. In fact, a plurality of first axial chambersformed as annular segments are provided in a circumferential direction,which restrict the radial movement of the damping fluid. The individualfirst axial chambers are typically each connected to the axial chamberon the other side that generally runs right around the circumference viaan individual axial channel. This other side is typically the connectionside, i.e. the side via which a load to be supported axially and dampedof a component to be mounted is introduced into the hydraulicallydamping bush bearing. The axial chambers can also be configured assub-divided in a circumferential direction on the connection side. Thus,an annular segment shaped axial chamber on the connection side can beassigned to each annular segment on the one side, wherein an axialchannel only connects annular segment shaped chambers assigned to oneanother on the connection and the other side.

Tests by the applicant have shown that the embodiment of a plurality ofaxial compensating chambers on the first side can improve the dampingcharacteristics of the hydraulically damping bush bearing, moreparticularly at frequencies ranging between 50 and 250 Hz.Unintentionally high damping, more particularly in radial loading, areprevented.

According to a preferred further embodiment of the embodiment as per theinvention, the first axial chambers spaced apart from one another in acircumferential direction are separated from one another by a partitionformed from the elastomeric damping member. Said partition typically hasthe contour of the first axial chambers in a transverse direction. It isassumed in particular here that the first axial chambers are formed by acounter-diaphragm, which is arranged typically at the end of the bush.Specifically and preferably, the counter-diaphragm forms an annularpassage running in a circumferential direction, which is configured witha constant cross-section in the circumferential direction. The partitionformed by the elastomeric damping member has a contour corresponding tosaid cross-section and extends into the annular channel such that theinner surface of the annular channel rests on the outer surface of thepartition in an initial state thus dividing and separating the firstaxial chambers from one another. In the event of excessive axial bearingpressure, where the damping fluid is displaced from the axial chambersprovided on the connection side to the compensating side, thecounter-diaphragm may, however, lift away from the partition thusremoving the separation. However, in the initial state, which isdependent on the pretension of the hydraulically damping bush bearing,the counter-diaphragm rests against the partition.

According to a further embodiment of the bush bearing as per theinvention, at least one fluid-free damping chamber is provided betweenthe axial chambers offset from one another in the axial direction, whichseparates the radial and axial chambers from one another. The axialchambers arranged offset from one another in an axial direction aretypically firstly the damping chamber provided on the connection sideand secondly, the axial compensating chamber provided typically on theopposite end of the bush bearing. The fluid-free damping chamber isfilled with a gas, more particularly air. The fluid-free damping chamberis typically sealed and consequently if the damping chamber iscompressed, the contents of the chamber are compressed and not expelledfrom the chamber. The fluid-free damping chamber is thus able to absorb,in particular higher axial load frequencies, by compressing the medium,generally a gas, which is introduced into the fluid-free dampingchamber. Thus, the hydraulic bush bearing as per the invention isrelatively soft even in the case of radial oscillations with higherfrequencies above 250 Hz. Unwanted high damping does not occur.

The fluid-free damping chamber is configured preferably continuously ina circumferential direction and consequently the fluid contained in thischamber can move freely in a circumferential direction in the event of acompensating movement. As a rule, this applies in the case of a radialstimulus. This is where the greatest effect occurs.

In the case of a compact further embodiment, the fluid-free dampingchamber is formed partly by the elastomeric damping member and partly bywalls of an intermediate diaphragm element attached to the elastomericdamping member. Said intermediate diaphragm element typically separatesthe fluid-free damping chamber from an axial chamber mounted upstreamaxially on one side that is generally directly adjacent thereto. Moreparticularly, this is the fluid or pump chamber arranged axially on theconnection side. In other words, the fluid-free damping chamber isgenerally arranged on the connection side of the elastomeric dampingmember.

The intermediate diaphragm element preferably has the task of sealing upand surrounding the fluid-free chamber. The intermediate diaphragmelement typically has a support ring on the inner peripheral surfacethereof for this purpose, which rests against the outer peripheralsurface of the inner part. On the outer circumference of theintermediate diaphragm element, the intermediate diaphragm element isreinforced preferably by an annular disc. Both the annular disc and thesupport ring are made from a hard material, such as a thermoplastic ormetal, and consequently they deform slightly at the very most when theintermediate diaphragm element is pressed into an annular passagebetween the bush and the inner part. The annular disc is configuredtypically as a core and encased in an elastomeric material which is alsovulcanised onto the outer peripheral surface of the support ring.

In a preferred manner directly adjacent to the outer peripheral surfaceof the support ring, the intermediate diaphragm element preferably formsan annular chamber segment, which forms an annular chamber of thefluid-free damping chamber. Moreover, as per a preferred furtherembodiment of the following invention, the intermediate diaphragmelement forms a sealing segment which can be placed onto the elastomericdamping member in a sealing manner. Said sealing segment typically restsagainst the elastomeric sealing member where said member is reinforcedby the aforementioned separator. In other words, the elastomeric dampingmember has a reinforcing element in the attachment region to the sealingsurface formed by the sealing segment, which reinforcing elementreinforces the elastomeric damping member, more particularly in an axialdirection, wherein said reinforcing element is typically formed by theseparator.

With a view to obtaining a good seal, the intermediate diaphragm elementis preferably configured such that an inner annular wall section of theannular chamber segment can be pushed onto the inner part and can befixed in an axial direction relative to the inner part such that, in anuntensioned initial state, the sealing segment projects in an offsetmanner relative to a front end of the annular wall section in thedirection of the elastomeric damping member. If it is assumed forreasons of simplicity that the inner part forms an annular contactsurface for axial fixing of the inner annular wall section, whichcontact surface is level with the attachment region formed by theelastomeric damping member for the sealing segment, then in anuntensioned state of the intermediate diaphragm element, the sealingsurface projects above the front end of the inner annular wall sectionresting against the annular surface. If the intermediate diaphragmelement is fitted now, the sealing segment first rests on the attachmentregion of the elastomeric damping member. When the intermediatediaphragm element is pushed forward in an axial direction into the finalinstallation position predetermined radially by the annular surface ofthe inner part, the elastomeric material of the intermediate diaphragmelement stores the axial tension between the intermediate diaphragmelements produced in the process, which pushes the sealing segmentagainst the elastomeric damping member. This action increases thetightness between the intermediate diaphragm element and the elastomericdamping member and consequently the axial chamber provided on the otherside of the intermediate diaphragm element can extend in a radialdirection beyond the damping member and the sealing segment does notnecessarily have to be provided between the elastomeric damping memberand an element provided on the end side for exerting axial pressure onthe radial outer surface of the intermediate diaphragm element. Theaxial chamber delimited by the intermediate diaphragm element can extendfurther outwards in a radial manner in this embodiment.

With a view to restricting movement in a radial direction, moreparticularly universal displacement, by compressing the fluid-freedamping chamber, a stop element arranged in the fluid-free dampingchamber is suggested as per a preferred further embodiment. Generally,at least two stop elements are implemented, which are opposite oneanother in a radial direction. The stop element is preferably connectedto the intermediate diaphragm element here and interacts with theelastomeric damping member. Consequently, a cushioned and soft stoppingaction can be achieved through the material properties of theelastomeric damping member, whereas the stop element itself can be madeof a hard material, such as a standard thermoplastic, for example.

The stop element is produced preferably as a separate component andconnected to a core of the intermediate diaphragm element. This core ismore particularly the aforementioned annular disc of the intermediatediaphragm element which can be made from a harder material. The stopelement and/or core can be made from plastic, wherein at least one ofthe elements, in the case of a two-part configuration, has one or morepins formed thereon as an integral piece for connecting both parts.

Further details and advantages of the following invention are providedin the description below of an exemplary embodiment in connection withthe drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a longitudinal view of the exemplary embodiment;

FIG. 2 shows a further longitudinal view of the exemplary embodiment,which is offset 90 degrees compared with FIG. 1;

FIG. 3 shows a perspective, partially cropped view of the exemplaryembodiment without the bush and;

FIG. 4 shows a perspective exploded view of the exemplary embodiment.

DETAILED DESCRIPTION OF THE INVENTION

The figures show an exemplary embodiment of a hydraulically damping bushbearing with a bush (reference sign 2), which is arranged concentricallyto an inner part 4, which passes through the bush 2. The bush 2 has alarger diameter on a connection side (reference sign 6) and essentiallyforms two cylinder sections, which are connected to one another by meansof an abutment shoulder 8. The connection side of the bush 2 with thelarger diameter includes an axial bearing diaphragm (reference sign 10),which is reinforced by a retaining ring 12 on the outer circumferencethereof and by a support lug 14 on the inner circumference thereof. Theretaining ring 12 and the support lug 14 are connected to theelastomeric material forming the bearing diaphragm 10 by vulcanisation.The single-piece bearing diaphragm element 16 formed in this way ispressed into the annular passage between the bush 2 and the inner part4. The bush 2 is also flattened down on the stop side thereof andoverlaps the retaining ring 12. Within this flattened down region, thebearing diaphragm 10 forms a bump stop 18 on each of the oppositeperipheral sections, over which an axial stop plate 20 projects, whichis assigned to the inner part 4 and connected thereto, and which acts inan axial manner on the underside of the bush bearing. The axial stopplate 20 rests on an annular section of the support lug 14 extending ina radial direction.

On the top side (reference sign 22) opposite the stop connection side 6,the bush 2 is covered by an axial counter diaphragm 24, which, like thepreviously described bearing diaphragm 10, is annular in shape and isreinforced radially inwards by a support ring 26 and radially outwardsby a retaining ring 28. Also located on said top side 22 is anintegrative counter diaphragm element formed by vulcanisation andconnection of support ring 26, retaining ring 28 and axial counterdiaphragm 24, which element forms an upper axial bump stop 30 which ispressed in a radial direction into the annular passage between the bush2 and the inner part 4. The inner part 4 forms a counter diaphragmabutment shoulder 32 against which the elastomeric material of thecounter diaphragm 24 rests in a sealing manner under the pressure of thesupport ring 26 pressed onto the inner part 4.

An elastomeric damping member 34 is provided axially within the upperaxial bump stop 30 and surrounding the inner part 4, which dampingmember is formed from an elastomeric material and into which a separator36 formed from a sheet metal material is vulcanised and forms radialchamber walls 35. Said separator 36 extends substantially over theentire axial reach of the elastomeric damping member 34. As can be seenparticularly in FIG. 2, the separator 36 reinforces a contact surfaceformed by the elastomeric damping member 34 for attaching the countermember element 30 at the level of the retaining ring 24, which is fixedin an axial direction by a flattened down area of the bush. Thisproduces a solid seal between the elastomeric damping member 34 and thecounter diaphragm element 30. Moreover, on this side, the elastomericdamping member forms partitions (reference sign 38) in a radialdirection on opposing sides, the contour of which partitions correspondsto the contour of an annular channel 40 formed by the counter diaphragm(see FIG. 1, FIG. 3). Thus, the annular channel 40 is divided in thecircumferential direction into two first axial chambers 42 that aresubstantially the same size, which are identified as separate axialchambers 42 a, 42 b in FIG. 2. Said axial chambers 42 a,b extend in thecircumferential direction at an angle of approximately 160 degrees.

The annular channel 40 communicates with a recess 44 formed on the frontend of the elastomeric damping member, which recess, like the annularchannel 40, is divided into peripheral sections by the partition 38. Therecess sections separated from one another in a circumferentialdirection belong to the two first axial chambers 42 a, 42 b.

A corresponding recess 46 is moulded on the opposite front end of theelastomeric damping member 34. Said recess 46 is covered by anintermediate diaphragm element (reference sign 48) which comprises anintermediate diaphragm 50 extending substantially in a radial direction,an intermediate diaphragm support ring 52, an annular disc 50 forming acore of the intermediate diaphragm element 48 as well as stop elements(reference sign 56), which are opposite each other in a radial direction(see FIG. 2). To form the intermediate diaphragm element, firstly theintermediate diaphragm support ring 52 and the annular disc 54 aresurrounded with elastomeric material, wherein a contact surface is leftopen for the stop elements 56. The annular disc 54 is positioned in amoulding tool using spacer cams 60, which are formed as a single-pieceon the annular disc 54 in radially opposing regions (see FIG. 2). Theintermediate diaphragm 50 is formed after the vulcanisation of theelastomeric material. The stop elements 56 are then connected to theannular disc by means of the pins 58. In an assembled state (see FIG.2), the stops 56 project into the recess 46.

On the outer circumference thereof, the intermediate diaphragm element48 is clamped between an inner annular surface 62 of the bush 2 formedby the abutment shoulder 8 and a front end on the outer circumference ofthe bearing diaphragm element 16. The axial reach of the retaining ring12 is reduced at the level of the spacer cams 60 and consequently saidretaining ring is surrounded there by the elastomeric material of thebearing diaphragm 10 (see FIG. 2). Otherwise, the retaining ring 12extends axially in a circumferential direction to the inner front end ofthe bearing diaphragm element 16. The retaining ring 12 clamps theannular disc 54 surrounded by elastomeric material between itself andthe inner annular surface 62 in a sealing manner. Thus on the outer sideof the intermediate diaphragm element 48, an axial chamber 64 acting asa pump chamber is formed and closed in a sealing manner between theintermediate diaphragm element 48 and the bearing diaphragm element 16.

Between the intermediate diaphragm support ring 52 and the inner edge ofthe annular disc 54, the intermediate diaphragm element 48 forms anannular chamber segment 66, which projects over a connection-side frontend 68 formed by the inner part 4, in an axial direction and towards theaxial chamber 64 and encloses an annular chamber 70 which communicateswith the recess 64. A fluid-free damping chamber 72 is formed as aresult, which is formed in a circular manner in the circumferentialdirection. Said fluid-free damping chamber 72 is sealed in an airtightmanner. For this purpose, the intermediate diaphragm element 48 with theelastomeric casing of the annular disc 54 rests against an attachmentregion (reference sign 74) of the elastomeric damping member 34, whichis reinforced in an axial direction by the separator 36 as a reinforcingelement. The sealing is performed radially inwards by the intermediatediaphragm support ring 52 pressed against the inner part 4, which clampsthe elastomeric material of the intermediate diaphragm element 48 in asealing manner between itself and the connection-side front end 68. Theintermediate diaphragm support ring 52 thereby forms an inner annularwall section 76 with the elastomeric material of the intermediatediaphragm 50 vulcanised thereon, which annular wall section is pushedand pressed onto the inner part 4 here and fixed in an axial directionby attachment onto the connection-side front end 68 opposite the innerpart 4.

The intermediate diaphragm 50 is thus formed such that in an assembledstate, a sealing segment 78 of the intermediate diaphragm element 48formed essentially by the annular disc 54 and the elastomeric casingthereof rests against the attachment region 74 under pretension. If theintermediate diaphragm element shown in the exemplary embodiment wereprovided as such, due to the design of the intermediate diaphragm 50,the sealing segment 78 would project over the front end of the annularwall section 76 abutting the connection-side front end 68 in anassembled state, i.e. would project in an offset manner. Said offset iseliminated entirely when the intermediate diaphragm element 48 is fittedunder elastic pretension of the flexible walls of the annular chambersegment 66, and consequently the front end of the annular wall section76 is arranged at more or less the same level as a sealing surface 80formed by the annular segment 78 and interacting with the attachmentregion 74 of the elastomeric damping member 34. This axial pretensioningof the intermediate diaphragm element 48 improves the tightness betweensaid element 48 and the elastomeric damping member 34.

As can be seen in FIGS. 2 and 3, the elastomeric damping member 34 formsradially opposing radial stop contours 82 on opposing peripheralsections, in which contours additional elements (reference sign 84) arelocated which are made from thermoplastic. The exemplary embodimentshown has two additional elements 84 a, 84 b, which are each formed inthe manner of a half ring and fitted together in the sectional planeshown in FIG. 2. The additional elements 84 rest against the innerperipheral surface of the bush 2 in a sealing manner and enclose aradial channel (reference sign 86) and an axial channel (reference sign88) there. Moreover, circular holes can be seen inside the additionalelements 84 a, b in FIG. 2. Both additional elements 84 a, b areinterconnected there using pins and consequently an essentiallycylindrical component is produced by both additional elements 84 (seeFIG. 3). A radial chamber 90 is enclosed between the radial stopcontours 82 and the inner peripheral surface of the additional elements84. Said radial chambers 90 a, 90 b communicate with one another via theradial channel 86. This configuration can be seen particularly in FIG.3. The figure also shows the course of the axial channel 88, which opensout into the pump chamber 64 through a channel section 88 a extendingsubstantially in an axial direction and then crosses over to aperipheral section 88 b extending virtually entirely along the outerside of the additional elements 84. At the end of said peripheralsection 88 b, the axial chamber 88 divides into two channel branches 88c, 88 d, of which one channel branch 88 c opens out into one of thefirst axial chambers 42 a and the other channel branch 88 d opens outinto the other of the first axial chambers 42 b. Thus, each of the firstaxial chambers 42 a, 42 b, on the top side of the bearing 22 isconnected to the axial chamber 64 arranged on the connection side 6 viathe axial channel 88.

Practical tests carried out by the applicant have shown that dividingthe axial chambers provided on one top side of the bearing 22 into aplurality of independent axial chamber sections 42 a, 42 b, separatedfrom one another in a circumferential direction, can improve the dampingcharacteristics of the bearing when it is exposed to a radial stimulus.More particularly, the bearing proves to be less rigid at highfrequencies. This effect can be increased even more if required bydividing the pump chamber 64 provided on the connection sideaccordingly. Thus, it is perfectly conceivable using partitions in acircumferential direction to divide the pump chamber into discretesegments separate from one another, which are formed as part of theintermediate diaphragm element 48 from the elastomeric material of theintermediate diaphragm element 48 and pass through the annular passageconfigured between said element and the bearing diaphragm element 16, asshown for example in FIG. 1. In such a case, the axial channel section88 a would also be divided into two channel branches and connected tothe relevant individual pump chamber segments.

In the examplary embodiment shown, the individual elements are onlyconnected by pressing them together or turning them around. Moreparticularly, no bonded connection is provided between the elastomericdamping member 34 and the counter diaphragm element 30 and theintermediate diaphragm element 48 respectively. The connection betweenthe intermediate diaphragm element 48 and the bearing diaphragm element16 is not fusion bonded either, but is simply a tensionally lockedconnection.

The additional elements 84 restrict the radial compensating movement ofthe bush bearing in a manner known per se and thus serve as a radialretainer. The lower axial bump stop 18 described above restricts anywobbling movement of the axial stop plate 20 relative to the bush 2.

LIST OF REFERENCE NUMERALS

-   2 Bush-   4 Inner part-   6 Connection side-   8 Abutment shoulder-   10 Bearing diaphragm, axial-   12 Retaining ring-   14 Support lug-   16 Bearing diaphragm element-   18 Bump stop, axial, lower-   20 Stop plate, axial-   22 Top side of bearing-   24 Counter diaphragm-   26 Support ring-   28 Retaining ring-   30 Counter diaphragm element-   32 Counter diaphragm abutment shoulder-   34 Elastomeric damping member-   35 Radial chamber wall-   36 Separator-   38 Partition-   40 Annular channel-   42 First axial chambers-   44 Recess-   46 Recess-   48 Intermediate diaphragm element-   50 Intermediate diaphragm-   52 Intermediate diaphragm support ring-   54 Annular disc-   56 Stop element-   58 Pin-   60 Spacer cams-   62 Inner annular surface-   64 Axial chamber/pump chamber-   66 Annular chamber segment-   68 Connection-side front end-   70 Annular chamber-   72 Fluid-free damping chamber-   74 Attachment region-   76 Annular wall section-   78 Damping segment-   80 Sealing surface-   82 Radial stop contour-   84 Additional element-   84 a Additional element-   84 b Additional element-   86 Radial channel-   88 Axial channel-   88 a Axial channel section-   88 b Peripheral section-   88 c Channel branch-   88 d Channel branch-   90 Radial chamber

The invention claimed is:
 1. A hydraulically damping bush bearing,comprising: an elongated inner part; an outer bush; an elastomericdamping member arranged between the outer bush and the inner part; apair of axial offset chambers defined in the bush bearing, the axialoffset chambers being offset from one another in an axial direction ofthe inner part and communicating with one another via at least one axialchannel; and a pair of radial chambers defined in the bush bearing, theradial chambers communicating via at least one radial channel, theradial chambers being disposed between the pair of axial offset chambersand offset from each other in a circumferential direction of the innerpart; a counter diaphragm; wherein one of the pair of axial offsetchambers has at least two separated first axial chambers spaced at adistance from one another in the circumferential direction; wherein theat least two separated first axial chambers are separated from oneanother by a partition formed on the elastomeric damping member; andwherein the counter diaphragm delimits the first axial chambers andrests on the partition of the elastomeric damping member in the axialdirection.
 2. A hydraulically damping bush bearing according to claim 1,further comprising at least one fluid-free damping chamber disposedbetween the pair of axial offset chambers.
 3. A hydraulically dampingbush bearing according to claim 2, wherein the at least one fluid-freedamping chamber extends continuously in a circumferential direction. 4.A hydraulically damping bush bearing according to claim 2, furthercomprising: an intermediate diaphragm element positioned on theelastomeric damping member; and wherein the at least one fluid-freedamping chamber is delimited in part by the elastomeric damping memberand in part by walls of the intermediate diaphragm element.
 5. Ahydraulically damping bush bearing according to claim 4, wherein theintermediate diaphragm element has an annular chamber segment forming anannular chamber of the fluid-free damping chamber, the intermediatediaphragm element further having a damping segment attached to theelastomeric damping member in a sealing manner.
 6. A hydraulicallydamping bush bearing according to claim 5, wherein the intermediatediaphragm element is configured such that an inner annular wall sectionof the annular chamber segment is pushed onto the inner part and isfixed in an axial direction relative to the inner part such that, in anuntensioned state, the damping segment projects in an offset mannerrelative to a front end of the annular wall section, the front end ofthe annular wall section being toward the elastomeric damping member. 7.A hydraulically damping bush bearing according to claim 5, wherein theelastomeric damping member is reinforced in an attachment region of asealing surface of the damping segment with at least one reinforcingelement extending substantially in an axial direction.
 8. Ahydraulically damping bush bearing according to claim 4, furthercomprising at least one stop element connected to the intermediatediaphragm element so as to interact with the elastomeric damping member.9. A hydraulically damping bush bearing according to claim 8, whereinthe stop element is produced as a separate component and is connected toan annular disc of the intermediate diaphragm element.
 10. Ahydraulically damping bush bearing according to claim 1, wherein thecounter diaphragm is arranged at an axial end of the outer bush.
 11. Ahydraulically damping bush bearing according to claim 1, wherein thecounter diaphragm lifts away from the partition when subject toexcessive axial bearing pressure.
 12. A hydraulically damping bushbearing comprising: an elongated inner part; an outer bush; anelastomeric damping member arranged between the outer bush and the innerpart; a pair of axial offset chambers defined in the bush bearing, theaxial offset chambers being offset from one another in an axialdirection of the inner part and communicating with one another via atleast one axial channel; and a pair of radial chambers defined in thebush bearing, the radial chambers communicating via at least one radialchannel, the radial chambers being disposed between the pair of axialoffset chambers and offset from each other in a circumferentialdirection of the inner part; wherein one of the pair of axial offsetchambers has at least two separated first axial chambers spaced at adistance from one another in the circumferential direction; at least onefluid-free damping chamber disposed between the pair of axial offsetchambers; an intermediate diaphragm element positioned on theelastomeric damping member; and wherein the at least one fluid-freedamping chamber is delimited in part by the elastomeric damping memberand in part by walls of the intermediate diaphragm element.